What are the differences between Combination and Half cell electrodes?

Document ID

Document ID TE11264

Published Date

Published Date 31/10/2019
Question
What are the differences between Combination and Half cell electrodes?
Summary
Combination vs half-cell probes
Answer
Potentiometric Electrochemical Measurement Systems (which are used for parameters like pH, Oxidation Reduction Potential (ORP), and Ion Selective Electrodes (ISE)) consist of three parts: A meter, a reference electrode, and a sensing electrode.

Which parameter is being measured is determined by the sensing electrode. The sensing electrode can be either a half cell, or a combination electrode.

Half cell probes are just the sensing electrode which would need to be used in addition to a separate reference probe. All half cell electrodes available from Hach are analog and use either a BNC connector or S7 screw cap. Reference electrodes commonly use a banana connector or S7 screw cap.

Combination probes are one probe that have both the sensing cell and reference cell build into one probe. All digital probes available from Hach are combination probes, but analog combination probes are available as well with either BNC connectors or S7 screw caps. Digital probes use connectors specific to the instrument line.

The benefit of half cells is that the sensing electrode and reference electrode can be replaced separately. The benefit of combination electrodes is that the system is simplified with less parts. There are also advantages and disadvantages of analog vs digital probes. Combination electrodes are much more commonly used currently. Half cell systems are an older more antiquated way of doing it.